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Molecular logic of neocortical projection neuron specification, development and diversity

Key Points

  • The sophisticated circuitry of the neocortex is assembled from a diverse repertoire of neuronal subtypes generated during development under precise molecular regulation, forming distinct functional areas within the tangential expanse of the neocortex. This collection of specialized neurons is produced by various progenitors with distinct morphological and molecular properties and with distinct patterns of cell division.

  • The lineages leading from progenitor cells to specific neuronal subtypes and the molecular mechanisms that determine the fixed order in which neuronal subtypes are generated remain largely unknown. Recent work suggests that some subtypes of neurons are produced by lineage-committed progenitors, although a number of models of lineage commitment can be entertained on the basis of current evidence.

  • Area identity acquisition is initiated by diffusible factors released from the periphery of the neocortical domain and subsequent induction of graded expression of arealizing transcription factors in ventricular zone progenitors. These progenitor-based controls establish a coordinate system of positional information that anchors area identity to specific rostrocaudal and mediolateral positions, which must then be transmitted to their neuronal progeny to be interpreted by a second network of transcription factors that direct postmitotic acquisition of area identity.

  • Projection neuron subtype identity is progressively established by extensive transcriptional cross-repression between genetic programmes driving the development of one subtype of projection neuron and those driving the development of alternative subtypes. These competing regulators sort newly postmitotic projection neurons into one of three broad subtype identities: corticothalamic, subcerebral and callosal.

  • Postmitotic regulators, including Lmo4 (LIM domain only 4) and Bhlhb5 (basic helix–loop–helix domain-containing, class B5), transform continuous gradients of positional information inherited from progenitors into sharp areal boundaries, instruct the formation of sensory maps and direct projection neurons to acquire areally appropriate phenotypic characteristics.

  • Over the course of evolution, a growing number of transcription factors were progressively recruited to control cortical development, gradually adding layers of neuronal diversity and areal specialization to a simpler ancestral framework.

  • The emerging understanding of the expression and function of key molecular regulators is beginning to illuminate a molecular logic underlying subtype and area identity acquisition. We propose that the order- and dose-dependent nature of projection neuron identity specification can be formalized by analogy to first-order Boolean logic, with decision points represented by 'molecular logic gates'.

Abstract

The sophisticated circuitry of the neocortex is assembled from a diverse repertoire of neuronal subtypes generated during development under precise molecular regulation. In recent years, several key controls over the specification and differentiation of neocortical projection neurons have been identified. This work provides substantial insight into the 'molecular logic' underlying cortical development and increasingly supports a model in which individual progenitor-stage and postmitotic regulators are embedded within highly interconnected networks that gate sequential developmental decisions. Here, we provide an integrative account of the molecular controls that direct the progressive development and delineation of subtype and area identity of neocortical projection neurons.

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Figure 1: Neocortical projection neurons are generated in an 'inside-out' fashion by diverse progenitor types in the VZ and SVZ.
Figure 2: Models of deep-layer and superficial-layer projection neuron production by distinct progenitor lineages.
Figure 3: Transcription factors in the VZ establish an area identity fate map.
Figure 4: Competing molecular programmes direct differentiation of newly postmitotic projection neurons into one of three broad subtype identities.
Figure 5: Postmitotic regulators set up sharp gene expression boundaries between cortical areas and direct area-specific phenotypic differentiation of projection neurons.

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References

  1. Parnavelas, J. G. The origin and migration of cortical neurones: new vistas. Trends Neurosci. 23, 126–131 (2000).

    Article  CAS  PubMed  Google Scholar 

  2. Wichterle, H., Turnbull, D. H., Nery, S., Fishell, G. & Alvarez-Buylla, A. In utero fate mapping reveals distinct migratory pathways and fates of neurons born in the mammalian basal forebrain. Development 128, 3759–3771 (2001).

    CAS  PubMed  Google Scholar 

  3. Cobos, I., Puelles, L. & Martinez, S. The avian telencephalic subpallium originates inhibitory neurons that invade tangentially the pallium (dorsal ventricular ridge and cortical areas). Dev. Biol. 239, 30–45 (2001).

    Article  CAS  PubMed  Google Scholar 

  4. Wonders, C. P. & Anderson, S. A. The origin and specification of cortical interneurons. Nature Rev. Neurosci. 7, 687–696 (2006).

    Article  CAS  Google Scholar 

  5. Gorski, J. A. et al. Cortical excitatory neurons and glia, but not GABAergic neurons, are produced in the Emx1-expressing lineage. J. Neurosci. 22, 6309–6314 (2002).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  6. Molyneaux, B. J., Arlotta, P., Menezes, J. R. L. & Macklis, J. D. Neuronal subtype specification in the cerebral cortex. Nature Rev. Neurosci. 8, 427–437 (2007).

    Article  CAS  Google Scholar 

  7. Batista-Brito, R. & Fishell, G. The developmental integration of cortical interneurons into a functional network. Curr. Top. Dev. Biol. 87, 81–118 (2009).

    Article  PubMed  PubMed Central  Google Scholar 

  8. Fishell, G. & Rudy, B. Mechanisms of inhibition within the telencephalon: “where the wild things are”. Annu. Rev. Neurosci. 34, 535–567 (2011).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  9. Corbin, J. G. & Butt, S. J. B. Developmental mechanisms for the generation of telencephalic interneurons. Dev. Neurobiol. 71, 710–732 (2011).

    Article  CAS  PubMed  Google Scholar 

  10. Migliore, M. & Shepherd, G. M. Opinion: an integrated approach to classifying neuronal phenotypes. Nature Rev. Neurosci. 6, 810–818 (2005).

    Article  CAS  Google Scholar 

  11. Spruston, N. Pyramidal neurons: dendritic structure and synaptic integration. Nature Rev. Neurosci. 9, 206–221 (2008).

    Article  CAS  Google Scholar 

  12. Oberlaender, M. et al. Cell type-specific three-dimensional structure of thalamocortical circuits in a column of rat vibrissal cortex. Cereb. Cortex 22, 2375–2391 (2012).

    Article  PubMed  Google Scholar 

  13. Defelipe, J. et al. New insights into the classification and nomenclature of cortical GABAergic interneurons. Nature Rev. Neurosci. 14, 202–216 (2013).

    Article  CAS  Google Scholar 

  14. Wichterle, H., Gifford, D., & Mazzoni, E. Mapping neuronal diversity one cell at a time. Science 341, 726–727 [2013].

    Article  CAS  PubMed  Google Scholar 

  15. Haubensak, W., Attardo, A., Denk, W. & Huttner, W. B. Neurons arise in the basal neuroepithelium of the early mammalian telencephalon: a major site of neurogenesis. Proc. Natl Acad. Sci. USA 101, 3196–3201 (2004).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  16. Noctor, S. C., Martínez-Cerdeño, V., Ivic, L. & Kriegstein, A. R. Cortical neurons arise in symmetric and asymmetric division zones and migrate through specific phases. Nature Neurosci. 7, 136–144 (2004).

    Article  CAS  PubMed  Google Scholar 

  17. Noctor, S. C., Martínez-Cerdeño, V. & Kriegstein, A. R. Contribution of intermediate progenitor cells to cortical histogenesis. Arch. Neurol. 64, 639–642 (2007).

    Article  PubMed  Google Scholar 

  18. Rakic, P. Guidance of neurons migrating to the fetal monkey neocortex. Brain Res. 33, 471–476 (1971).

    Article  CAS  PubMed  Google Scholar 

  19. Noctor, S. C., Flint, A. C., Weissman, T. A., Dammerman, R. S. & Kriegstein, A. R. Neurons derived from radial glial cells establish radial units in neocortex. Nature 409, 714–720 (2001).

    Article  CAS  PubMed  Google Scholar 

  20. Miyata, T., Kawaguchi, A., Okano, H. & Ogawa, M. Asymmetric inheritance of radial glial fibers by cortical neurons. Neuron 31, 727–741 (2001).

    Article  CAS  PubMed  Google Scholar 

  21. Hansen, D. V., Lui, J. H., Parker, P. R. L. & Kriegstein, A. R. Neurogenic radial glia in the outer subventricular zone of human neocortex. Nature 464, 554–561 (2010).

    Article  CAS  PubMed  Google Scholar 

  22. Fietz, S. A. et al. OSVZ progenitors of human and ferret neocortex are epithelial-like and expand by integrin signaling. Nature Neurosci. 13, 690–699 (2010).

    Article  CAS  PubMed  Google Scholar 

  23. Wang, X., Tsai, J.-W., LaMonica, B. & Kriegstein, A. R. A new subtype of progenitor cell in the mouse embryonic neocortex. Nature Neurosci. 14, 555–561 (2011). References 21 and 23 identify a novel subpopulation of radial glia that lack an apical process and have expanded dramatically in primates to establish an outer SVZ.

    Article  CAS  PubMed  Google Scholar 

  24. Martínez-Cerdeño, V. et al. Comparative analysis of the subventricular zone in rat, ferret and macaque: evidence for an outer subventricular zone in rodents. PLoS ONE 7, e30178 (2012).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  25. Wu, S.-X. et al. Pyramidal neurons of upper cortical layers generated by NEX-positive progenitor cells in the subventricular zone. Proc. Natl Acad. Sci. USA 102, 17172–17177 (2005).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  26. Sessa, A., Mao, C.-A., Hadjantonakis, A.-K., Klein, W. H. & Broccoli, V. Tbr2 directs conversion of radial glia into basal precursors and guides neuronal amplification by indirect neurogenesis in the developing neocortex. Neuron 60, 56–69 (2008).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  27. Kowalczyk, T. et al. Intermediate neuronal progenitors (basal progenitors) produce pyramidal-projection neurons for all layers of cerebral cortex. Cereb. Cortex 19, 2439–2450 (2009).

    Article  PubMed  PubMed Central  Google Scholar 

  28. Angevine, J. B. & Sidman, R. L. Autoradiographic study of cell migration during histogenesis of cerebral cortex in the mouse. Nature 192, 766–768 (1961).

    Article  PubMed  Google Scholar 

  29. Rakic, P. Neurons in rhesus monkey visual cortex: systematic relation between time of origin and eventual disposition. Science 183, 425–427 (1974).

    Article  CAS  PubMed  Google Scholar 

  30. Marin-Padilla, M. Dual origin of the mammalian neocortex and evolution of the cortical plate. Anat. Embryol. 152, 109–126 (1978).

    Article  CAS  Google Scholar 

  31. Raedler, E. & Raedler, A. Autoradiographic study of early neurogenesis in rat neocortex. Anat. Embryol. 154, 267–284 (1978).

    Article  CAS  Google Scholar 

  32. Luskin, M. B. & Shatz, C. J. Studies of the earliest generated cells of the cat's visual cortex: cogeneration of subplate and marginal zones. J. Neurosci. 5, 1062–1075 (1985).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  33. McConnell, S. K. Fates of visual cortical neurons in the ferret after isochronic and heterochronic transplantation. J. Neurosci. 8, 945–974 (1988).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  34. McConnell, S. K. & Kaznowski, C. E. Cell cycle dependence of laminar determination in developing neocortex. Science 254, 282–285 (1991).

    Article  CAS  PubMed  Google Scholar 

  35. Frantz, G. D. & McConnell, S. K. Restriction of late cerebral cortical progenitors to an upper-layer fate. Neuron 17, 55–61 (1996).

    Article  CAS  PubMed  Google Scholar 

  36. Luskin, M. B., Pearlman, A. L. & Sanes, J. R. Cell lineage in the cerebral cortex of the mouse studied in vivo and in vitro with a recombinant retrovirus. Neuron 1, 635–647 (1988).

    Article  CAS  PubMed  Google Scholar 

  37. Walsh, C. & Cepko, C. L. Clonally related cortical cells show several migration patterns. Science 241, 1342–1345 (1988).

    Article  CAS  PubMed  Google Scholar 

  38. Price, J. & Thurlow, L. Cell lineage in the rat cerebral cortex: a study using retroviral-mediated gene transfer. Development 104, 473–482 (1988).

    CAS  PubMed  Google Scholar 

  39. Reid, C. B., Liang, I. & Walsh, C. Systematic widespread clonal organization in cerebral cortex. Neuron 15, 299–310 (1995).

    Article  CAS  PubMed  Google Scholar 

  40. Shen, Q. et al. The timing of cortical neurogenesis is encoded within lineages of individual progenitor cells. Nature Neurosci. 9, 743–751 (2006).

    Article  CAS  PubMed  Google Scholar 

  41. Eiraku, M. et al. Self-organized formation of polarized cortical tissues from ESCs and its active manipulation by extrinsic signals. Cell Stem Cell 3, 519–532 (2008).

    Article  CAS  PubMed  Google Scholar 

  42. Gaspard, N. et al. An intrinsic mechanism of corticogenesis from embryonic stem cells. Nature 455, 351–357 (2008). The authors of references 41 and 42 direct differentiation of mouse embryonic stem cells into telencephalic progenitors in monolayer cultures relying exclusively on pharmacological agents and morphogens. Embryonic stem cell-derived cortical progenitors are able to generate different projection neuron subtypes in the appropriate temporal order.

    Article  CAS  PubMed  Google Scholar 

  43. Nasu, M. et al. Robust formation and maintenance of continuous stratified cortical neuroepithelium by laminin-containing matrix in mouse ES cell culture. PLoS ONE 7, e53024 (2012).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  44. Inoue, K., Terashima, T., Nishikawa, T. & Takumi, T. Fez1 is layer-specifically expressed in the adult mouse neocortex. Eur. J. Neurosci. 20, 2909–2916 (2004).

    Article  PubMed  Google Scholar 

  45. Hirata, T. et al. Zinc finger gene fez-like functions in the formation of subplate neurons and thalamocortical axons. Dev. Dyn. 230, 546–556 (2004).

    Article  CAS  PubMed  Google Scholar 

  46. Arlotta, P. et al. Neuronal subtype-specific genes that control corticospinal motor neuron development in vivo. Neuron 45, 207–221 (2005). The authors of this study purify individual neuronal populations on the basis of their axonal projections to define subtype-specific developmental programmes. By focusing on genes expressed by corticospinal motor neurons, but not closely related CPN, the authors identify candidate molecular controls over subtype development, including the transcription factor CTIP2.

    Article  CAS  PubMed  Google Scholar 

  47. Molyneaux, B., Arlotta, P., Hirata, T., Hibi, M. & Macklis, J. D. Fezl is required for the birth and specification of corticospinal motor neurons. Neuron 47, 817–831 (2005). In references 47, 48 and 85 Fezf2 was the first transcription factor identified to specify the identity of one neocortical projection neuron subtype (SCPN).

    Article  CAS  PubMed  Google Scholar 

  48. Chen, J.-G., Rasin, M.-R., Kwan, K. Y. & Sestan, N. Zfp312 is required for subcortical axonal projections and dendritic morphology of deep-layer pyramidal neurons of the cerebral cortex. Proc. Natl Acad. Sci. USA 102, 17792–17797 (2005).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  49. Nieto, M. et al. Expression of Cux-1 and Cux-2 in the subventricular zone and upper layers II–IV of the cerebral cortex. J. Comp. Neurol. 479, 168–180 (2004).

    Article  CAS  PubMed  Google Scholar 

  50. Zimmer, C., Tiveron, M.-C., Bodmer, R. & Cremer, H. Dynamics of Cux2 expression suggests that an early pool of SVZ precursors is fated to become upper cortical layer neurons. Cereb. Cortex 14, 1408–1420 (2004).

    Article  PubMed  Google Scholar 

  51. Molyneaux, B. J. et al. Novel subtype-specific genes identify distinct subpopulations of callosal projection neurons. J. Neurosci. 29, 12343–12354 (2009).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  52. Franco, S. J. et al. Fate-restricted neural progenitors in the mammalian cerebral cortex. Science 337, 746–749 (2012). Genetic fate-mapping of Cux2 -expressing cells enables the authors to establish that a subset of cortical progenitors, which are present from the earliest stages of corticogenesis, are committed to generating 'upper-layer' (commissural and associative) neurons.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  53. Grove, E. A. & Fukuchi-Shimogori, T. Generating the cerebral cortical area map. Annu. Rev. Neurosci. 26, 355–380 (2003).

    Article  CAS  PubMed  Google Scholar 

  54. Crossley, P. H. & Martin, G. R. The mouse Fgf8 gene encodes a family of polypeptides and is expressed in regions that direct outgrowth and patterning in the developing embryo. Development 121, 439–451 (1995).

    CAS  PubMed  Google Scholar 

  55. Shimamura, K. & Rubenstein, J. L. Inductive interactions direct early regionalization of the mouse forebrain. Development 124, 2709–2718 (1997).

    CAS  PubMed  Google Scholar 

  56. Maruoka, Y. et al. Comparison of the expression of three highly related genes, Fgf8, Fgf17 and Fgf18, in the mouse embryo. Mech. Dev. 74, 175–177 (1998).

    Article  CAS  PubMed  Google Scholar 

  57. Bachler, M. & Neubüser, A. Expression of members of the Fgf family and their receptors during midfacial development. Mech. Dev. 100, 313–316 (2001).

    Article  CAS  PubMed  Google Scholar 

  58. Grove, E. A., Tole, S., Limon, J., Yip, L. & Ragsdale, C. W. The hem of the embryonic cerebral cortex is defined by the expression of multiple Wnt genes and is compromised in Gli3-deficient mice. Development 125, 2315–2325 (1998).

    CAS  PubMed  Google Scholar 

  59. Assimacopoulos, S., Grove, E. A. & Ragsdale, C. W. Identification of a Pax6-dependent epidermal growth factor family signaling source at the lateral edge of the embryonic cerebral cortex. J. Neurosci. 23, 6399–6403 (2003).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  60. Fukuchi-Shimogori, T. & Grove, E. A. Neocortex patterning by the secreted signaling molecule FGF8. Science 294, 1071–1074 (2001).

    Article  CAS  PubMed  Google Scholar 

  61. Toyoda, R. et al. FGF8 acts as a classic diffusible morphogen to pattern the neocortex. Development 137, 3439–3448 (2010).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  62. Garel, S., Huffman, K. J. & Rubenstein, J. L. R. Molecular regionalization of the neocortex is disrupted in Fgf8 hypomorphic mutants. Development 130, 1903–1914 (2003).

    Article  CAS  PubMed  Google Scholar 

  63. Cholfin, J. A. & Rubenstein, J. L. R. Patterning of frontal cortex subdivisions by Fgf17. Proc. Natl Acad. Sci. USA 104, 7652–7657 (2007).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  64. Assimacopoulos, S., Kao, T., Issa, N. P. & Grove, E. A. Fibroblast growth factor 8 organizes the neocortical area map and regulates sensory map topography. J. Neurosci. 32, 7191–7201 (2012). The authors use early microelectroporations of Fgf8 into ectopic sites to demonstrate that the mature cortical area pattern is organized during development by a finely tuned FGF8 signalling gradient.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  65. Walther, C. & Gruss, P. Pax-6, a murine paired box gene, is expressed in the developing CNS. Development 113, 1435–1449 (1991).

    CAS  PubMed  Google Scholar 

  66. Gulisano, M., Broccoli, V., Pardini, C. & Boncinelli, E. Emx1 and Emx2 show different patterns of expression during proliferation and differentiation of the developing cerebral cortex in the mouse. Eur. J. Neurosci. 8, 1037–1050 (1996).

    Article  CAS  PubMed  Google Scholar 

  67. Waclaw, R. R. et al. The zinc finger transcription factor Sp8 regulates the generation and diversity of olfactory bulb interneurons. Neuron 49, 503–516 (2006).

    Article  CAS  PubMed  Google Scholar 

  68. Sahara, S., Kawakami, Y., Izpisua Belmonte, J. C. & O'Leary, D. D. M. Sp8 exhibits reciprocal induction with Fgf8 but has an opposing effect on anterior–posterior cortical area patterning. Neural Dev. 2, 10 (2007).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  69. Liu, Q., Dwyer, N. D. & O'Leary, D. D. Differential expression of COUP-TFI, CHL1, and two novel genes in developing neocortex identified by differential display PCR. J. Neurosci. 20, 7682–7690 (2000).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  70. Zhou, C., Tsai, S. Y. & Tsai, M. J. COUP-TFI: an intrinsic factor for early regionalization of the neocortex. Genes Dev. 15, 2054–2059 (2001).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  71. Hamasaki, T., Leingärtner, A., Ringstedt, T. & O'Leary, D. D. M. EMX2 regulates sizes and positioning of the primary sensory and motor areas in neocortex by direct specification of cortical progenitors. Neuron 43, 359–372 (2004).

    Article  CAS  PubMed  Google Scholar 

  72. Armentano, M. et al. COUP-TFI regulates the balance of cortical patterning between frontal/motor and sensory areas. Nature Neurosci. 10, 1277–1286 (2007). Using conditional deletion of Couptf1 in the neocortex, the authors demonstrate that the size and position of cortical areas are primarily determined by cortex-autonomous genetic programmes.

    Article  CAS  PubMed  Google Scholar 

  73. Bishop, K. M., Goudreau, G. & O'Leary, D. D. Regulation of area identity in the mammalian neocortex by Emx2 and Pax6. Science 288, 344–349 (2000).

    Article  CAS  PubMed  Google Scholar 

  74. Muzio, L. & Mallamaci, A. Emx1, Emx2 and Pax6 in specification, regionalization and arealization of the cerebral cortex. Cereb. Cortex 13, 641–647 (2003).

    Article  PubMed  Google Scholar 

  75. Zembrzycki, A., Griesel, G., Stoykova, A. & Mansouri, A. Genetic interplay between the transcription factors Sp8 and Emx2 in the patterning of the forebrain. Neural Dev. 2, 8 (2007).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  76. Borello, U. et al. Sp8 and COUP-TF1 reciprocally regulate patterning and Fgf signaling in cortical progenitors. Cereb. Cortex http://dx.doi.org/10.1093/cercor/bhs412 (2013).

  77. Rakic, P. Specification of cerebral cortical areas. Science 241, 170–176 (1988).

    Article  CAS  PubMed  Google Scholar 

  78. Elsen, G. E. et al. The protomap is propagated to cortical plate neurons through an Eomes-dependent intermediate map. Proc. Natl Acad. Sci. USA 110, 4081–4086 (2013).

    Article  PubMed  PubMed Central  Google Scholar 

  79. Gray, P. A. et al. Mouse brain organization revealed through direct genome-scale TF expression analysis. Science 306, 2255–2257 (2004).

    Article  CAS  PubMed  Google Scholar 

  80. Visel, A., Thaller, C. & Eichele, G. GenePaint.org: an atlas of gene expression patterns in the mouse embryo. Nucleic Acids Res. 32, D552–D556 (2004).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  81. Magdaleno, S. et al. BGEM: an in situ hybridization database of gene expression in the embryonic and adult mouse nervous system. PLoS Biol. 4, e86 (2006).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  82. Lein, E. S. et al. Genome-wide atlas of gene expression in the adult mouse brain. Nature 445, 168–176 (2007).

    Article  CAS  PubMed  Google Scholar 

  83. Sugino, K. et al. Molecular taxonomy of major neuronal classes in the adult mouse forebrain. Nature Neurosci. 9, 99–107 (2006).

    Article  CAS  PubMed  Google Scholar 

  84. Visel, A. et al. A high-resolution enhancer atlas of the developing telencephalon. Cell 152, 895–908 (2013).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  85. Chen, B., Schaevitz, L. R. & McConnell, S. K. Fezl regulates the differentiation and axon targeting of layer 5 subcortical projection neurons in cerebral cortex. Proc. Natl Acad. Sci. USA 102, 17184–17189 (2005).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  86. Bedogni, F. et al. Tbr1 regulates regional and laminar identity of postmitotic neurons in developing neocortex. Proc. Natl Acad. Sci. USA 107, 13129–13134 (2010).

    Article  PubMed  PubMed Central  Google Scholar 

  87. McKenna, W. L. et al. Tbr1 and Fezf2 regulate alternate corticofugal neuronal identities during neocortical development. J. Neurosci. 31, 549–564 (2011). The authors show that Tbr1 regulates CThPN development in large part by repressing transcription of Fezf2.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  88. Chen, B. et al. The Fezf2Ctip2 genetic pathway regulates the fate choice of subcortical projection neurons in the developing cerebral cortex. Proc. Natl Acad. Sci. USA 105, 11382–11387 (2008).

    Article  PubMed  PubMed Central  Google Scholar 

  89. Rouaux, C. & Arlotta, P. Direct lineage reprogramming of post-mitotic callosal neurons into corticofugal neurons in vivo. Nature Cell Biol. 15, 214–221 (2013).

    Article  CAS  PubMed  Google Scholar 

  90. Alcamo, E. A. et al. Satb2 regulates callosal projection neuron identity in the developing cerebral cortex. Neuron 57, 364–377 (2008).

    Article  CAS  PubMed  Google Scholar 

  91. Britanova, O. et al. Satb2 is a postmitotic determinant for upper-layer neuron specification in the neocortex. Neuron 57, 378–392 (2008). References 90 and 91 (back-to-back papers) identified Satb2 as the first transcriptional regulator to control the generation of CPN.

    Article  CAS  PubMed  Google Scholar 

  92. Lai, T. et al. SOX5 controls the sequential generation of distinct corticofugal neuron subtypes. Neuron 57, 232–247 (2008).

    Article  CAS  PubMed  Google Scholar 

  93. Tomassy, G. S. et al. Area-specific temporal control of corticospinal motor neuron differentiation by COUP-TFI. Proc. Natl Acad. Sci. USA 107, 3576–3581 (2010).

    Article  PubMed  PubMed Central  Google Scholar 

  94. Han, W. et al. TBR1 directly represses Fezf2 to control the laminar origin and development of the corticospinal tract. Proc. Natl Acad. Sci. USA 108, 3041–3046 (2011).

    Article  PubMed  PubMed Central  Google Scholar 

  95. Kwan, K. Y. et al. SOX5 postmitotically regulates migration, postmigratory differentiation, and projections of subplate and deep-layer neocortical neurons. Proc. Natl Acad. Sci. USA 105, 16021–16026 (2008).

    Article  PubMed  PubMed Central  Google Scholar 

  96. Shim, S., Kwan, K. Y., Li, M., Lefebvre, V. & Sestan, N. Cis-regulatory control of corticospinal system development and evolution. Nature 486, 74–79 (2012). The authors identify an evolutionarily conserved cortex-specific enhancer for Fezf2 expression, together with the SOXC transcription factors that bind this enhancer to drive Fezf2 expression.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  97. Koester, S. E. & O'Leary, D. D. Connectional distinction between callosal and subcortically projecting cortical neurons is determined prior to axon extension. Dev. Biol. 160, 1–14 (1993).

    Article  CAS  PubMed  Google Scholar 

  98. Lodato, S. et al. Excitatory projection neuron subtypes control the distribution of local inhibitory interneurons in the cerebral cortex. Neuron 69, 763–779 (2011).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  99. Srinivasan, K. et al. A network of genetic repression and derepression specifies projection fates in the developing neocortex. Proc. Natl Acad. Sci. USA 109, 19071–19078 (2012).

    Article  PubMed  PubMed Central  Google Scholar 

  100. Baranek, C. et al. Protooncogene Ski cooperates with the chromatin-remodeling factor Satb2 in specifying callosal neurons. Proc. Natl Acad. Sci. USA 109, 3546–3551 (2012).

    Article  PubMed  PubMed Central  Google Scholar 

  101. Deck, M. et al. Pathfinding of corticothalamic axons relies on a rendezvous with thalamic projections. Neuron 77, 472–484 (2013).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  102. Sohur, U. S., Padmanabhan, H. K., Kotchetkov, I. S., Menezes, J. R. L. & Macklis, J. D. Anatomic and molecular development of corticostriatal projection neurons in mice. Cereb. Cortex http://dx.doi.org/10.1093/cercor/bhs342 (2012).

  103. Azim, E., Shnider, S. J., Cederquist, G. Y., Sohur, U. S. & Macklis, J. D. Lmo4 and Clim1 progressively delineate cortical projection neuron subtypes during development. Cereb. Cortex 19 (Suppl. 1), i62–i69 (2009).

    Article  PubMed  PubMed Central  Google Scholar 

  104. Lickiss, T., Cheung, A. F. P., Hutchinson, C. E., Taylor, J. S. H. & Molnár, Z. Examining the relationship between early axon growth and transcription factor expression in the developing cerebral cortex. J. Anat. 220, 201–211 (2012).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  105. Molnár, Z. & Cordery, P. Connections between cells of the internal capsule, thalamus, and cerebral cortex in embryonic rat. J. Comp. Neurol. 413, 1–25 (1999).

    Article  PubMed  Google Scholar 

  106. Cederquist, G. Y., Azim, E., Shnider, S. J., Padmanabhan, H. & Macklis, J. D. Lmo4 establishes rostral motor cortex projection neuron subtype diversity. J. Neurosci. 33, 6321–6332 (2013).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  107. Huang, Z. et al. Transcription factor Lmo4 defines the shape of functional areas in developing cortices and regulates sensorimotor control. Dev. Biol. 327, 132–142 (2009).

    Article  CAS  PubMed  Google Scholar 

  108. Kashani, A. H. et al. Calcium activation of the LMO4 transcription complex and its role in the patterning of thalamocortical connections. J. Neurosci. 26, 8398–8408 (2006).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  109. Joshi, P. S. et al. Bhlhb5 regulates the postmitotic acquisition of area identities in layers II–V of the developing neocortex. Neuron 60, 258–272 (2008). The authors demonstrate that the transcription factor Bhlhb5 acts postmitotically to regulate refinement of molecular area identity and extension of corticospinal axons.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  110. Weimann, J. M. et al. Cortical neurons require Otx1 for the refinement of exuberant axonal projections to subcortical targets. Neuron 24, 819–831 (1999).

    Article  CAS  PubMed  Google Scholar 

  111. Ando, K. et al. Establishment of framework of the cortical area is influenced by Otx1. Neurosci. Res. 60, 457–459 (2008).

    Article  CAS  PubMed  Google Scholar 

  112. Chou, S.-J. et al. Geniculocortical input drives genetic distinctions between primary and higher-order visual areas. Science 340, 1239–1242 (2013).

    Article  CAS  PubMed  Google Scholar 

  113. Brodmann, K. & Garey, L. J. Brodmann's Localisation in the Cerebral Cortex (Springer, 2006).

    Google Scholar 

  114. Pinto, L. et al. AP2γ regulates basal progenitor fate in a region- and layer-specific manner in the developing cortex. Nature Neurosci. 12, 1229–1237 (2009).

    Article  CAS  PubMed  Google Scholar 

  115. Lukaszewicz, A. et al. G1 phase regulation, area-specific cell cycle control, and cytoarchitectonics in the primate cortex. Neuron 47, 353–364 (2005).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  116. Rakic, P. Evolution of the neocortex: a perspective from developmental biology. Nature Rev. Neurosci. 10, 724–735 (2009).

    Article  CAS  Google Scholar 

  117. Molnár, Z. Evolution of cerebral cortical development. Brain Behav. Evol. 78, 94–107 (2011).

    Article  PubMed  Google Scholar 

  118. Medina, L. & Reiner, A. Do birds possess homologues of mammalian primary visual, somatosensory and motor cortices? Trends Neurosci. 23, 1–12 (2000).

    Article  CAS  PubMed  Google Scholar 

  119. Aboitiz, F. & Montiel, J. One hundred million years of interhemispheric communication: the history of the corpus callosum. Braz. J. Med. Biol. Res. 36, 409–420 (2003).

    Article  CAS  PubMed  Google Scholar 

  120. Cheung, A. F. P. et al. The subventricular zone is the developmental milestone of a 6-layered neocortex: comparisons in metatherian and eutherian mammals. Cereb. Cortex 20, 1071–1081 (2010).

    Article  PubMed  Google Scholar 

  121. Abdel-Mannan, O., Cheung, A. F. P. & Molnár, Z. Evolution of cortical neurogenesis. Brain Res. Bull. 75, 398–404 (2008).

    Article  CAS  PubMed  Google Scholar 

  122. Fame, R. M., MacDonald, J. L. & Macklis, J. D. Development, specification, and diversity of callosal projection neurons. Trends Neurosci. 34, 41–50 (2011).

    Article  CAS  PubMed  Google Scholar 

  123. Kaas, J. H. Evolution of somatosensory and motor cortex in primates. Anat. Rec. A Discov. Mol. Cell. Evol. Biol. 281, 1148–1156 (2004).

    Article  PubMed  Google Scholar 

  124. Kaas, J. H. Reconstructing the areal organization of the neocortex of the first mammals. Brain Behav. Evol. 78, 7–21 (2011).

    Article  PubMed  Google Scholar 

  125. Bulchand, S., Subramanian, L. & Tole, S. Dynamic spatiotemporal expression of LIM genes and cofactors in the embryonic and postnatal cerebral cortex. Dev. Dyn. 226, 460–469 (2003).

    Article  CAS  PubMed  Google Scholar 

  126. Sun, T. et al. Early asymmetry of gene transcription in embryonic human left and right cerebral cortex. Science 308, 1794–1798 (2005).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  127. Ozdinler, P. H. et al. Corticospinal motor neurons and related subcerebral projection neurons undergo early and specific neurodegeneration in hSOD1G93A transgenic ALS mice. J. Neurosci. 31, 4166–4177 (2011).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  128. Strong, M. J. & Gordon, P. H. Primary lateral sclerosis, hereditary spastic paraplegia and amyotrophic lateral sclerosis: discrete entities or spectrum? Amyotroph. Lateral Scler. Other Motor Neuron Disord. 6, 8–16 (2005).

    Article  PubMed  Google Scholar 

  129. Singer, M. A., Statland, J. M., Wolfe, G. I. & Barohn, R. J. Primary lateral sclerosis. Muscle Nerve 35, 291–302 (2007).

    Article  CAS  PubMed  Google Scholar 

  130. Harding, A. E. Classification of the hereditary ataxias and paraplegias. Lancet 1, 1151–1155 (1983).

    Article  CAS  PubMed  Google Scholar 

  131. Salinas, S., Proukakis, C., Crosby, A. & Warner, T. T. Hereditary spastic paraplegia: clinical features and pathogenetic mechanisms. Lancet Neurol. 7, 1127–1138 (2008).

    Article  CAS  PubMed  Google Scholar 

  132. Watanabe, K. et al. Directed differentiation of telencephalic precursors from embryonic stem cells. Nature Neurosci. 8, 288–296 (2005).

    Article  CAS  PubMed  Google Scholar 

  133. Espuny-Camacho, I. et al. Pyramidal neurons derived from human pluripotent stem cells integrate efficiently into mouse brain circuits in vivo. Neuron 77, 440–456 (2013). This study shows that neurons derived from human induced pluripotent stem cells can establish appropriate patterns of axonal connectivity, dendritic arborization and functional circuit integration when transplanted into mouse brains.

    Article  CAS  PubMed  Google Scholar 

  134. Rouaux, C. & Arlotta, P. Fezf2 directs the differentiation of corticofugal neurons from striatal progenitors in vivo. Nature Neurosci. 13, 1345–1347 (2010).

    Article  CAS  PubMed  Google Scholar 

  135. De la Rossa, A. et al. In vivo reprogramming of circuit connectivity in postmitotic neocortical neurons. Nature Neurosci. 16, 193–200 (2013). References 89 and 135 demonstrate that Fezf2 can postmitotically reprogramme the output connectivity of superficial-layer CPN and the input connectivity of layer IV granular neurons, respectively.

    Article  CAS  PubMed  Google Scholar 

  136. Joosten, E. A., Gribnau, A. A. & Dederen, P. J. An anterograde tracer study of the developing corticospinal tract in the rat: three components. Brain Res. 433, 121–130 (1987).

    Article  CAS  PubMed  Google Scholar 

  137. Woodworth, M. B., Greig, L. C., Kriegstein, A. R. & Macklis, J. D. SnapShot: cortical development. Cell 151, 918–918. e1 (2012).

    Article  CAS  PubMed  Google Scholar 

  138. Toresson, H., Potter, S. S. & Campbell, K. Genetic control of dorsal-ventral identity in the telencephalon: opposing roles for Pax6 and Gsh2. Development 127, 4361–4371 (2000).

    CAS  PubMed  Google Scholar 

  139. Stoykova, A., Treichel, D., Hallonet, M. & Gruss, P. Pax6 modulates the dorsoventral patterning of the mammalian telencephalon. J. Neurosci. 20, 8042–8050 (2000).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  140. Muzio, L. et al. Conversion of cerebral cortex into basal ganglia in Emx2−/−Pax6Sey/Sey double-mutant mice. Nature Neurosci. 5, 737–745 (2002).

    Article  CAS  PubMed  Google Scholar 

  141. Yoshida, M. et al. Emx1 and Emx2 functions in development of dorsal telencephalon. Development 124, 101–111 (1997).

    CAS  PubMed  Google Scholar 

  142. Schuurmans, C. & Guillemot, F. Molecular mechanisms underlying cell fate specification in the developing telencephalon. Curr. Opin. Neurobiol. 12, 26–34 (2002).

    Article  CAS  PubMed  Google Scholar 

  143. Azim, E., Jabaudon, D., Fame, R. M. & Macklis, J. D. SOX6 controls dorsal progenitor identity and interneuron diversity during neocortical development. Nature Neurosci. 12, 1238–1247 (2009).

    Article  CAS  PubMed  Google Scholar 

  144. Monuki, E. S., Porter, F. D. & Walsh, C. A. Patterning of the dorsal telencephalon and cerebral cortex by a roof plate-Lhx2 pathway. Neuron 32, 591–604 (2001).

    Article  CAS  PubMed  Google Scholar 

  145. Chou, S.-J., Perez-Garcia, C. G., Kroll, T. T. & O'Leary, D. D. M. Lhx2 specifies regional fate in Emx1 lineage of telencephalic progenitors generating cerebral cortex. Nature Neurosci. 12, 1381–1389 (2009).

    Article  CAS  PubMed  Google Scholar 

  146. Hanashima, C., Li, S. C., Shen, L., Lai, E. & Fishell, G. Foxg1 suppresses early cortical cell fate. Science 303, 56–59 (2004).

    Article  CAS  PubMed  Google Scholar 

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Acknowledgements

This work was supported by grants from the US National Institutes of Health (NIH) (NS045523 and NS075672, NS041590, and NS049553), the Harvard Stem Cell Institute and the Massachusetts Spinal Cord Research Program to J.D.M. M.B.W. was partially supported by US NIH individual predoctoral National Research Service Award NS064730 and the DEARS Foundation. L.C.G. was partially supported by the Harvard Medical Scientist Training Program and USNIH individual predoctoral National Research Service Award NS080343.

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Correspondence to Jeffrey D. Macklis.

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Glossary

Hodology

The path followed by axons to reach their targets.

Lineages

The shared ancestries of cells that can be traced back to a common progenitor through sequential cell divisions.

Neuroepithelial cells

Neuroectodermal progenitors that are the main proliferative cell type of the early neocortex. They later differentiate into radial glial cells.

Gyrencephalic

Having a folded cerebral cortex, with gyri (ridges) and sulci (furrows).

Competence

The differentiation potential of a cell, as determined by its intrinsic molecular state.

Fate-mapping

Labelling a progenitor cell with a permanent and heritable mark to identify all of its progeny.

FLP knock-in line

A mouse line in which expression of FLP recombinase is driven by the promoter of a gene of interest.

Morphogens

Secreted factors that can induce at least two different cell fates in a concentration-dependent manner by forming a gradient.

Fasciculation

Bundling together of axons that project to a common final or intermediate target through adhesive interactions.

Cajal–Retzius cells

Early-born cortical neurons that express the glycoprotein reelin and reside in layer I.

Enhancer element

A short region of DNA, typically occupied by multiple transcription factors, which is sufficient to drive expression of a gene with temporal and/or cell-type specificity.

Chromatin remodelling

Changes in the three-dimensional structure of chromatin brought about by epigenetic modifications. These structural changes can result in either transcriptional activation or silencing of genes located in the involved chromatin segment.

Barrels

Cylindrical columns of neurons in layer IV of the neocortex that receive and process sensory input from a single whisker. The topographical organization of the barrels in the cortex corresponds precisely to the arrangement of whisker follicles on the snout.

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Greig, L., Woodworth, M., Galazo, M. et al. Molecular logic of neocortical projection neuron specification, development and diversity. Nat Rev Neurosci 14, 755–769 (2013). https://doi.org/10.1038/nrn3586

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